Add the voltage and lateral accel curvature pass

We now have enough math here to now talk about the lateral acceleration
and the max velocity to only use a 12 volt battery.

Change-Id: I13330a1f164e751276c12c18cdc61b629d4295df
diff --git a/frc971/control_loops/python/polydrivetrain.py b/frc971/control_loops/python/polydrivetrain.py
index 29fdeef..c87c1e6 100644
--- a/frc971/control_loops/python/polydrivetrain.py
+++ b/frc971/control_loops/python/polydrivetrain.py
@@ -132,6 +132,12 @@
     self.U_max = self._drivetrain.U_max
     self.U_min = self._drivetrain.U_min
 
+  @property
+  def robot_radius_l(self):
+    return self._drivetrain.robot_radius_l
+  @property
+  def robot_radius_r(self):
+    return self._drivetrain.robot_radius_r
 
 class VelocityDrivetrain(object):
   HIGH = 'high'